Squirrels, with their bushy tails and agile movements, are a common sight in many parts of the world. While they’re often seen nibbling on nuts or darting up trees, few of us stop to consider the power behind those tiny teeth.
How strong is a squirrel’s bite, and why is it important to know?
Quick Answer: “The bite force of a squirrel has been scientifically measured to be 72.95 Newtons which is the same as 16.39 pounds force.”
Keep reading to figure out exactly:
- How this value was determined
- Why the value changes between different squirrel species
- What this much force feels like
How The Bite Force of a Squirrel Was Measured
Researchers captured wild squirrels and other rodents in cages and let them bite a small sensor before being released. Multiple measurements were taken.
The sensor used was developed by https://doi.org/10.1644/07-MAMM-A-101R.1and is described in the journal article, Measuring Bite Force in Small Mammals with a Piezo-Resistive Sensor Journal of Mammalogy, Volume 89, Issue 2, 18 April 2008, Pages 513–517,
The Two Factors that Influence the Bite Force of Rodents
The collection of bite force data from different rodents led to a surprising discovery.
It was previously thought that the biggest factor determining the force was the physical size of the rodent. It intuitively makes sense that a large rodent would bite harder than a small rodent. However, when the researchers crunched the data they realized that the squirrel was biting much harder than expected based upon size alone.
What they eventually discovered is that the bite force could be accurately predicted by the size of the rodents incisors. That is, the size of the teeth was a better indicator of bite force than the size of the animal.
The scientists developed a mathematical model where maximal bite force was estimated from complete incisors using an incisor strength index (Zi) where:
Zi = ((antero-posterior length of incisor)2 x (medio-lateral width of incisor))/6
Bite Force across Rodentia, ((log10(bite force) = 0.566 log10 (Zi) + 1.432, R2 = 0.956
The diagram below, from this journal article, shows exactly where to measure the rodents teeth to determine the Incisor Strength Index, Zi.
What makes this finding so remarkable is that it allows scientists to calculate the bite force of different rodents simply by examining their skeletal remains.
Comparisons Between Squirrels
It is tempting to tale the measured bite force value of 72.95 Newtons and call it a day but that would be a mistake.
You see, the squirrel the researchers used in the study was a fox squirrel that weighed about 1.3 pounds. Fox squirrels are the largest tree squirrels in the United States and have some pretty massive teeth.
Consider the measure value of 72.95 Newtons as the upper range of squirrel bite strength instead of the average.
Comparisons Across Species
To most of us the term 72 Newtons does not have an intuitive meaning. Just how strong of a bite is that?
For comparison here are the bite strengths that you might be familiar with:
- Human Bite Strength: 253 N (women), 285 N (men)
- 75 Pound German Shepherd Bite Strength: 628 N
- House Cat Bite Force: 78-120 N (depends on which teeth)
Putting things in perspective, a bite from a squirrel is in the same ballpark as getting bit by a cat but nowhere near as bad as being bitten by a dog or person.
Anatomy of a Squirrel’s Jaw
The jaw of a squirrel is a marvel of nature. It’s designed to be both strong and efficient. Central to their jaw are their incisors, which, like all rodents, continuously grow throughout their lives. This constant growth ensures that their teeth don’t wear down from all the gnawing and biting they do.
Supporting these teeth are powerful muscles that give the squirrel its biting strength. These muscles, combined with the leverage provided by the jaw’s structure, allow the squirrel to exert a significant amount of force when biting down.
Why Do Squirrels Need a Strong Bite?
Squirrels primarily feed on hard foods like nuts and seeds. To access the nutritious insides of these foods, they need to be able to crack through tough shells. A strong bite force allows them to do this efficiently.
Additionally, squirrels use their teeth for various other tasks. They might gnaw on branches to build their nests or even use their teeth as a means of defense when threatened. In both scenarios, having a powerful bite is advantageous.
The bite force of a squirrel is a testament to nature’s ability to equip creatures with the tools they need to survive and thrive. While they might appear small and harmless, squirrels possess a bite that’s both powerful and efficient.
Understanding these nuances of nature allows us to appreciate the intricate balance and design of the animal kingdom.